Editor's note: Biotech expert Adam Feuerstein will be the featured guest on TSC Live at noon EDT Tuesday, Sept. 29. Email your questions at firstname.lastname@example.org; tweet us on Twitter with hash tag #tsclive; or leave a message on our Facebook page. Bookmark the TSC Live page now.(Updated from Monday, Sept. 28) SAN DIEGO ( TheStreet) -- An independent investigation of the way Sequenom ( SQNM) conducted a study of its genetic test for Down syndrome found that the biotech firm "failed to provide adequate protocols and controls" and that the study's data were unreliable and misreported. The inquiry, conducted by special committe of the company's board, has led to an executive-suite purging. The company fired its chief executive, Harry Stylli, and its senior vice president of development, Elizabeth Dragon, effective immediately. Sequenom's board also "obtained the resignation" of the company's chief financial officer, Paul Hawran, as well as another as-yet-unnamed officer. "While each of these officers and employees has denied wrongdoing," the company said in a press release, "the special committee's investigation has raised serious concerns, resulting in a loss of confidence by the independent members of the company's board of directors in the personnel involved." The Sequenom board stopped short of asserting that any of the executives purposefully fudged the study's data. In after-market trading, shares of Sequenom shares plunged 44.6% to $3.15, after closing at $5.69 in the regular session. Sequenom first reported in April that data from studies of the company's test product for trisomy 21, the genetic condition that results in Down syndrome, were unreliable, citing "employee mishandling." The special committee launched its independent investigation shortly thereafter. The results of that probe, released after Monday's market close, appeared to corroborate the worst.